Facebook Inc. on Thursday launched an open-source hardware project to share what the company has learned about designing energy-reducing, cost-efficient computer servers and data centers with the entire technology industry.

Although the environmental activist group Greenpeace International still criticized the social media giant for relying on coal-generated electricity, Facebook officials said their Open Compute Project has already delivered a 38 percent increase in energy efficiency for 24 percent less cost.

"We think coal is actually a small issue in the grand scheme of energy efficiency," said Jonathan Heiliger, Facebook's vice president of technical operations. "Instead of worrying about what energy source you may choose and the impact of that source on the environment, the best way of improving CO{-2} (emissions) and improving the environment is to cut energy consumption."

The Palo Alto firm compared the project to the open-source software movement, which allows widespread collaboration on computer programs instead of relying on individual, proprietary development.

Facebook believes publishing technical specifications for the company-designed equipment used in its new Prineville, Ore., data center will inspire faster development of even more efficient servers, power supplies, server racks and buildings.

The equipment was co-developed with other tech heavyweights, including Advanced Micro Devices Inc., Dell Inc., Intel Corp. and Hewlett-Packard Co. Dell has already built servers based on the Open Compute specifications.

"We're not doing this in a dark closet somewhere, but we're sharing it with the world, we're sharing it with our peers," Heiliger said.

Data center energy costs are a major concern for Internet companies like Facebook , which has an estimated 600 million members worldwide. Facebook said that if one-quarter of U.S. data centers used Open Compute specifications, the energy saved could power more than 160,000 homes.

The company's $188 million, 147,000-square-foot Prineville center saved money by using less material, including paint, logos and stickers, and engineers examined details such as how to reduce power loss inside servers.

But Greenpeace has long criticized Facebook and the plant's utility provider, Pacific Power, which supplies some of the electricity from coal-burning plants.

Greenpeace climate campaigner Casey Harrell praised Facebook for its efforts, but said "efficiency is simply not enough."

"As the global warming footprint of the IT industry, and Facebook specifically, continues to grow significantly, a focus on energy efficiency alone will only slow the speeding train of unsustainable emissions growth," Harrell said in a statement. "If Facebook wants to be a truly green company, it needs to reduce its greenhouse gas emissions. The way to do that is decouple its growth from its emissions footprint by using clean, renewable energy to power its business instead of dirty coal and dangerous nuclear power."